Don't listen to this poster, PVC at cold temps is very brittle, the pieces are very hard to extract if they blow up because x-ray translucent. Its only rated fro 289 psi on water not compressed gases!
Yes a break across the threads isn't too exciting, but a longitudinal rupture is bad.
Also, PVC can break down over time when exposed to some other plastics, I can't recall if it gets brittle or goes soft but it will fail at lower pressures.
No reason to use it for air service.